The invention relates to an apparatus for the limitation of the full-load injection quantity in a supercharged internal combustion engine with fuel injection, with two pneumatic control elements, wherein one control element responds to the pressure differential between charge and atmospheric pressure to effect a charge-pressure-dependent limitation of the full-load injection quantity, and another control element embodied as a barometric cell is arranged to limit the full-load injection quantity in dependence on atmospheric pressure and both control elements act on the supply quantity adjustment member of the injection pump, and with at least one full-load stop which is disengageable for the attainment of an additional starting quantity which is greater than the full-load injection quantity.
The object of such an apparatus is to limit the full-load injection quantity of a supercharged internal combustion engine with fuel injection which is used to drive road vehicles in regions with extreme variations in elevation, in order to avoid smoke formation as a result of adapting to the load and atmospheric-pressure-dependent weight of the air charge of the cylinders.
A known apparatus of this type comprises two full-load stops which are associated with the regulator rod of the injection pump, one of which is controlled by a control element responsive to the differential between charge pressure and atmospheric pressure and the other is controlled by a control element which is embodied as a barometric cell.
These two full-load stops are each arranged on one regulator nose, in the regulator rod adjustment direction of minimum quantity, in such a way that the full-load injection quantity, up to a preset differential between charge pressure and atmospheric pressure, is limited independently of the charge pressure in accordance with the full-load stop controlled thereby and, beyond that preset pressure differential, independently of atmospheric pressure alone, by means of the full-load stop controlled by the barometric cell. So that the regulator rod can be brought into the starting quantity position to start the engine, both full-load stops must be arranged to be disengaged. Since each of the full-load stops further requires a separate disengagement actuation, which can either take place by means of the rpm transmitter of the regulator apparatus when the engine rpm fall below the minimum idling level, or by means of a hydraulic or electromagnetic control element, either automatically or by hand via a cable line or a rod, the known apparatus described above proves to be extraordinarily expensive, not only in cost to construct but time and effort to install.